Blood processing filter and the method for manufacturing the same

ABSTRACT

This invention relates to a blood processing filter comprising a sheet-like filter element, an inlet-side flexible container and an outlet-side flexible container that sandwich the filter element and are sealed thereto, an inlet port provided in the inlet-side flexible container for accepting blood before being processed by the filter element, and an outlet port provided in the outlet-side flexible container for discharging blood after being processed by the filter element. The blood processing filter also includes a flow channel securing sheet arranged between the filter element and the outlet-side flexible container. A flow channel hole through which blood processed by the filter element passes is formed in the flow channel securing sheet. The outlet port is provided so as to be capable of communicating with the flow channel hole.

CROSS-REFERENCE RELATED APPLICATIONS

The present application is a division of U.S. application Ser. No.13/237,029, filed Sep. 20, 2011, which is based on ProvisionalApplication No. 61/427,327 filed Dec. 27, 2010 and ProvisionalApplication No. 61/384,913 filed Sep. 21, 2010, the disclosures of whichincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to a blood processing filter for removingundesirable components such as aggregates and leukocytes from blood. Inparticular, the present invention relates to a precise and disposableblood processing filter for removing microaggregates and leukocyteswhich may cause side effects from whole blood preparations, erythrocytepreparations, thrombocyte preparations, blood plasma preparations andthe like for blood transfusion, as well as a method for manufacturingthe blood processing filter.

RELATED BACKGROUND ART

It is becoming common for whole blood collected from a donor to beseparated into blood component preparations such as an erythrocytepreparation, a thrombocyte preparation, and a blood plasma preparationand stored for transfusion. Since microaggregates and leukocytesincluded in these blood preparations cause various side effects duringblood transfusion, the number of occasions for removing theseundesirable components before blood transfusion has been increasing. Theneed for leukocyte removal has widely been recognized particularly inrecent years. Legislation regarding removal of leukocytes from all kindsof blood preparations for blood transfusion before being used fortransfusion has been introduced in an increasing number of countries.

The most common method of removing leukocytes from blood preparations isby processing blood preparations using a leukocyte removal filter.Conventionally, in many cases blood preparations processed using aleukocyte removal filter have been processed at the bedside when bloodtransfusion is performed. In recent years, however, to improve qualitycontrol of leukocyte-free preparations and efficiency of leukocyteremoval operations, it is more common, particularly in developedcountries, to process the blood preparations in blood centers beforestoring the blood preparations (pre-storage leukocyte removal).

A blood collection-separation set, typically consisting of two to fourflexible bags, a tube connecting these bags, an anticoagulant, anerythrocyte preservation solution, a blood collection needle, and thelike has been used for collecting blood from a donor, separating theblood into several blood components, and storing the blood components. Asystem in which a leukocyte removal filter is incorporated into such ablood collection-separation set has been widely used as an optimumsystem for the above-mentioned “pre-storage leukocyte removal”. Such asystem is called a “closed system” or an “integrated system” or thelike. Such systems are disclosed in Japanese Patent Laid-Open No.1-320064, International Publication No. WO 92/020428 and the like.

Conventionally, a filter element made from nonwoven fabric or a porousbody packed in a hard container of polycarbonate or the like has beenwidely used as a leukocyte removal filter. However, because thecontainer used in such a filter has a low level of air permeability,there is the problem that it is difficult to apply steam sterilization,which is widely used as a sterilization process in bloodcollection-separation sets. In one type of closed system, leukocytes arefirst removed from the whole blood preparation after collecting theblood. Subsequently, after the leukocyte removal filter is separated,the leukocyte-free blood is centrifuged for separation into variouscomponents. In another type of closed system, the whole blood is firstcentrifuged to be divided into various blood components, and then theleukocytes are removed. In the latter system, the leukocyte removalfilter is also centrifuged together with the blood collection-separationset. At such time, a hard container may damage bags and tubes, or thehard container itself may not withstand the stress and may break duringcentrifugation.

To solve these problems, flexible leukocyte removal filters have beendeveloped in which the container is made of a material having excellentflexibility and steam permeability that is the same as or similar to thematerial used for the bags of the blood collection-separation set. Theseflexible leukocyte removal filters that use a container made of amaterial having excellent flexibility and steam permeability are broadlyclassified into a type in which the filter element is welded to asheet-like flexible frame, which is then welded to a housing material(see European Patent Specification EP 0526678 and Japanese PatentLaid-Open No. 11-216179), and a type in which a flexible container isdirectly welded to the filter element (see Japanese Patent Laid-Open No.7-267871 and International Publication No. WO 95/17236). The former typemay be hereinafter referred to as “frame welding type” and the lattermay be referred to as “container welding type”.

Normally, when processing blood with these types of leukocyte removalfilters, a bag containing a blood preparation to be processed that isconnected to a blood inlet side of the filter via a tube is placed at aheight that is approximately 20 to 100 cm higher than the filter toallow the blood preparation to pass through the filter by the action ofgravity. After filtration, the blood preparation is stored in a recoverybag that is connected to a blood outlet side of the filter via a tube.During filtration, a pressure loss occurs due to the resistance of thefilter element, whereby the pressure in a space on the inlet side of thefilter becomes a positive pressure. In the case of the filter thatincludes a flexible container, there is a tendency for the flexibilityof the container itself to cause the container to swell like a balloondue to the positive pressure, thereby pressing the filter elementagainst the container on the outlet side.

Furthermore, normally, a bag for storing blood that has been processedwith the blood filter is placed at a position that is 50 to 100 cm lowerthan the filter, and blood moves through a channel on the downstreamside due to the action of gravity. Hence, there is a tendency for theoutlet side of the filter to become a negative pressure due to thisaction, and the flexible container is liable to adhere to the filterelement.

That is, it has been pointed out previously that in the case of a filterthat uses a flexible container, there is a problem that there is astrong tendency for the filter element to adhere to the outlet-sidecontainer due to a dual force, and as a result the flow of blood isobstructed and an adequate flow rate can not be obtained.

Various measures have been proposed to solve this problem.Representative examples of such measures include a method that inserts asoft polyvinyl chloride tube referred to as a “connecting rod” betweenthe filter element and the outlet-side container to prevent adherence(see European Patent Specification EP 0526678), a method that preventsadherence by providing concavities and convexities with verticalintervals of 0.2 mm to 2 mm on the internal surface of a soft container(Japanese Patent Laid-Open No. 11-216179), and a method that inserts ascreen made of knit fiber (International Publication No. WO 95/17236).

However, in a case in which a separate member such as a connecting rodor a screen is inserted, because it is required to perform weldingprecisely when welding the separate member to the container, there arethe problems that a welding defect may occur, the manufacturing processis complicated, and the manufacturing cost is increased by the use ofadditional materials.

Furthermore, in the case of providing concavities and convexities on theinternal surface of a container, there is the problem that theconcavities and convexities on the internal surface of the container mayinduce a welding defect or may decrease the pressure resistance when thecontainer material and the filter element are welded together.

Further, in a filter in which at least one of an inlet and an outlet isstraddled and sealed by a second seal part, as disclosed in EuropeanPatent Specification EP 0526678, Japanese Patent Laid-Open No.11-216179, and international Publication No. WO 04/050147, it isnecessary to use a complicated tool or process used for sealing.

As described above, when the conventional technology is investigatedfrom the point of view of a disadvantage caused by negative pressurethat arises on the filter outlet side, in other words, from the point ofview of how to secure a space that can serve as a passage for blood topass through between the container and the filter element that areattempting to adhere to each other, it is found that the conventionaltechnology is not necessarily satisfactory.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a blood processingfilter that, without leading to a risk of a welding defect, complicatingthe manufacturing process, or increasing costs, can avoid a situation inwhich a flow is inhibited and filtering performance is lowered due toadherence or the like between an outlet-side container and a filterelement of a flexible filter, can effectively utilize the entire filterelement, and can simultaneously achieve a high flow rate and highfiltering performance.

To solve the above described problems, the inventors of the presentinvention carried out studies with respect to the effects of the shapesof flexible containers, filter elements and the like of blood processingfilters and of the methods for assembling the blood processing filters,and succeeded in solving the above problems by providing a bloodprocessing filter that can alleviate a decrease in a flow and a declinein leukocyte removal performance that are caused by adherence between anoutlet-side container and a filter element that arises as a result of anegative pressure on a filter outlet side.

Specifically, the present invention relates to a blood processing filterincluding a sheet-like filter element, an inlet-side flexible containerand an outlet-side flexible container that sandwich the filter elementand are sealed thereto, an inlet port provided in the inlet-sideflexible container for accepting blood before being processed by thefilter element, and an outlet port provided in the outlet-side flexiblecontainer for discharging blood after being processed by the filterelement; the blood processing filter further including a flow channelsecuring sheet that is arranged between the filter element and theoutlet-side flexible container; wherein: a flow channel hole throughwhich blood that is processed by the filter element passes is formed inthe flow channel securing sheet, and the outlet port is provided so asto be capable of communicating with the flow channel hole. Note that,according to the present invention, the term “blood” includes bloodpreparations such as whole blood preparations, erythrocyte preparations,thrombocyte preparations and blood plasma preparations for bloodtransfusion. Further, according to the present invention, the term“capable of communicating” refers to, when a state in which blood isflowing is assumed, or when blood is actually flowing, a continuousempty space being formable in which adherence does not occur between anoutlet-side flexible container and another element.

According to this blood processing filter, even if a dual force that iscaused by a positive pressure on the inlet side and a negative pressureon the outlet side acts when filtering, a blood flow channel is securedbetween the flow channel hole in the flow channel securing sheet and theoutlet port. Accordingly, a situation in which a blood flow is inhibitedand filtering performance is lowered due to adherence or the likebetween the outlet-side flexible container and the filter element of theblood processing filter is avoided, the configuration is advantageous interms of effectively utilizing the entire filter element, and a highfiltering flow rate and high filtering performance can both be achievedin a compatible manner.

The above described blood processing filter can further include: a firstseal part that seals the inlet-side flexible container and the filterelement in a band shape, and that is provided so as to surround theinlet port; and an annular second seal part that seals at least theinlet-side flexible container and the outlet-side flexible container,and that is provided so as to surround the first seal part at a positionthat is closer to an outer edge than the first seal part; wherein avalley part corresponding to the first seal part is provided on anoutlet side of the filter element, and at least one portion of the flowchannel hole that is formed in the flow channel securing sheet isarranged in an empty space region that is formed by the valley part in astate in which blood is flowing.

The present invention can also provide a blood processing filteraccording to above described blood processing filter, in which aplurality of flow channel holes are formed in the flow channel securingsheet, and at least one portion of all of the flow channel holes isarranged in the empty space region that is formed by the valley part.

Further, the present invention can provide a blood processing filteraccording to above described blood processing filter, in which an outletopening that communicates with an inside of the outlet-side flexiblecontainer is formed in the outlet port, and at least one portion of theoutlet opening is arranged so as to overlap with at least one of theflow channel hole and the valley part.

The present invention can also provide a blood processing filteraccording to above described blood processing filter, in which thesecond seal part sandwiches and adheres the flow channel securing sheetbetween the inlet-side flexible container and the outlet-side flexiblecontainer.

Further, the present invention can provide a blood processing filteraccording to above described blood processing filter, in which the firstseal part sandwiches and adheres the filter element between theinlet-side flexible container and the flow channel securing sheet.

Furthermore, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which thesecond seal part sandwiches and adheres the flow channel securing sheetbetween the inlet-side flexible container and the outlet-side flexiblecontainer, and the first seal part sandwiches and adheres the filterelement between the inlet-side flexible container and the flow channelsecuring sheet.

In addition, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which theflow channel securing sheet is arranged so as to cover an effectivefiltering portion of the filter element, and a plurality of the flowchannel holes are formed in the flow channel securing sheet in a regionthat faces the effective filtering portion.

The present invention can also provide a blood processing filteraccording to the above described blood processing filter in which, inthe flow channel securing sheet, a proportion of a gross area of theflow channel holes with respect to an area of the effective filteringportion is between 30% and 99%.

Further, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which athickness of the flow channel securing sheet is between 0.1 mm and 3 mm.

Furthermore, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which athickness of the flow channel securing sheet is between 0.2 mm and 2 mm.

Further, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which athickness of the flow channel securing sheet is between 0.2 mm and 1.5mm.

In addition, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which theflow channel hole of the flow channel securing sheet is a slit shape,and a width of the flow channel hole is between 0.5 mm and 20 mm.

Further, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which theflow channel hole of the flow channel securing sheet is a slit shape,and a width of the flow channel hole is between 1 mm and 15 mm.

Furthermore, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which theflow channel hole of the flow channel securing sheet is a slit shape,and a width of the flow channel hole is between 1 mm and 10 mm.

In addition, the present invention can provide a blood processing filteraccording to the above described blood processing filter, that includes:a frame sheet that is arranged between the filter element and theinlet-side flexible container; a first seal part that, in a state inwhich the filter element is clamped by the frame sheet and the flowchannel securing sheet, seals the frame sheet, the filter element, andthe flow channel securing sheet in a band shape, and that is provided ina ring shape along a periphery of the filter element; and an openingthat is formed on an inner side that is surrounded by the first sealpart, of the frame sheet.

Further, the present invention can provide a blood processing filteraccording to the above described blood processing filter, that includesa valley part that is provided in correspondence to the first seal parton an outlet side of the filter element, wherein at least one portion ofthe flow channel hole formed in the flow channel securing sheet isarranged in an empty space region that is formed by the valley part in astate in which blood is flowing.

Furthermore, the present invention can provide a blood processing filteraccording to the above described blood processing filter, in which aplurality of the flow channel holes are formed in the flow channelsecuring sheet, and at least one portion of all of the flow channelholes is arranged in the empty space region that is formed by the valleypart.

The present invention also relates to a method for manufacturing a bloodprocessing filter that includes a sheet-like filter element, aninlet-side flexible container and an outlet-side flexible container thatsandwich the filter element and are sealed thereto, an inlet portprovided in the inlet-side flexible container for accepting blood beforebeing processed by the filter element, and an outlet port provided inthe outlet-side flexible container for discharging blood after beingprocessed by the filter element; the method including: an installingstep of arranging the inlet-side flexible container and the outlet-sideflexible container so as to sandwich the filter element, and arranging aflow channel securing sheet in which a flow channel hole is formedthrough which blood processed by the filter element passes, between thefilter element and the outlet-side flexible container; and a sealingstep of sealing the inlet-side flexible container and the outlet-sideflexible container in a state in which the filter element and the flowchannel securing sheet are arranged at predetermined positions in theinstalling step; wherein, in the installing step, the outlet port isarranged at a position at which the outlet port is capable ofcommunicating with the flow channel hole of the flow channel securingsheet.

Further, the present invention can provide a method for manufacturing ablood processing filter according to the above described method,wherein: the sealing step includes a first sealing step of forming afirst seal part that seals the inlet-side flexible container, the filterelement, and the flow channel securing sheet in a band shape so as tosurround an area where the inlet port is formed, without adhering thefilter element and the outlet-side flexible container, and a secondsealing step of sealing to form an annular second seal part so as tosurround the first seal part at a position that is closer to an outeredge than the first seal part; a band-shaped valley part correspondingto the first seal part is generated on an outlet side of the filterelement by the first sealing step; and in the installing step, the flowchannel securing sheet is arranged so that at least one portion of theflow channel hole formed in the flow channel securing sheet is arrangedin an empty space region that is formed by the valley part in a state inwhich blood is flowing.

Furthermore, the present invention can provide a method formanufacturing a blood processing filter according to the above describedmethod, in which an outlet opening that communicates with an inside ofthe outlet-side flexible container is formed in the outlet port, and inthe installing step, at least one portion of the outlet opening isarranged so as to overlap with at least one of the flow channel hole andthe valley part.

Further, the present invention can provide a method for manufacturing ablood processing filter according to the above described method, inwhich, in the second sealing step, the flow channel securing sheet issandwiched and adhered between the inlet-side flexible container and theoutlet-side flexible container, and in the first sealing step, thefilter element is sandwiched and adhered between the inlet-side flexiblecontainer and the flow channel securing sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view that illustrates one portion of a blood processingfilter according to a first embodiment of the present invention, that isshown in a cut-away manner;

FIG. 2 is a sectional view taken along a line II-II in FIG. 1;

FIG. 3 is a sectional view taken along a line III-III in FIG. 1;

FIG. 4 is a sectional view that illustrates, in an enlarged manner, anend of a flow channel hole of a flow channel securing sheet and aninside seal part;

FIG. 5 is a view that schematically illustrates a relationship between aportion corresponding to a valley part of a filter element and anotherportion;

FIG. 6 is a view that schematically illustrates a flow of blood insidean outlet-side container;

FIG. 7 is a front view that illustrates an outline of a blood processingsystem that includes a blood processing filter;

FIG. 8 is a sectional view that illustrates a state in which the bloodprocessing filter is used;

FIG. 9 is a sectional view that illustrates, in an enlarged manner, anend of a flow channel hole of a flow channel securing sheet and aninside seal part of a blood processing filter according to a secondembodiment of the present invention;

FIG. 10 is a plan view that illustrates one portion of a bloodprocessing filter according to a third embodiment of the presentinvention, that is shown in a cut-away manner; and

FIG. 11 is a sectional view of a blood processing filter according to afourth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described hereunder withreference to the drawings. Note that the term “blood” that is describedin each of the following embodiments includes blood preparations such aswhole blood preparations, erythrocyte preparations, thrombocytepreparations and blood plasma preparations for blood transfusion.Further, although various forms can be adopted for the external shape ofthe blood processing filter, such as a rectangular shape, a disc shape,an oval disc shape, and an elliptical shape, a rectangular shape ispreferable for decreasing loss of materials when the filters aremanufactured. Accordingly, in the following embodiments, an example inwhich the blood processing filter has a rectangular shape is described.

First, a blood processing filter 1A relating to a first embodiment ofthe present invention is described referring to FIGS. 1 to 3. The bloodprocessing filter 1A includes a flexible container 3 having an inletport 9 a and an outlet port 11 a for blood, a sheet-like filter element5 that is arranged so as to divide the inside of the flexible container3 into an inlet port 9 a side and an outlet port 11 a side, and a flowchannel securing sheet 7 that is arranged in an overlapping manner withrespect to the filter element 5.

The flexible container 3 has a rectangular, flat shape. Here, the term“flat shape” means a shape having a thin thickness and a wide surface.The flexible container 3 includes an inlet-side container 9 that has arectangular sheet shape, and an outlet-side container 11 that has arectangular sheet shape. An inlet port 9 a in which an inlet flowchannel 9 b that allows the inside and the outside to communicate isformed is sealed in the inlet-side container 9. An outlet port 11 a inwhich an outlet flow channel 11 b that allows the inside and the outsideto communicate is formed is sealed in the outlet-side container 11. Inthis connection, as used herein, the term “seal (to seal)” refers tofixing by bonding (including welding) to a degree that can preventleakage of a liquid. Further, the inlet-side container 9 is an exampleof an inlet-side flexible container, and the outlet-side container 11 isan example of an outlet-side flexible container.

The inlet-side container 9 and the outlet-side container 11 overlap witheach other through the rectangular filter element 5 and the rectangularflow channel securing sheet 7. The inlet-side container 9 is sealedalong the periphery of the filter element 5 in a state in which thefilter element 5 is clamped between the inlet-side container 9 and theflow channel securing sheet 7. A band-shaped bonding region along theperiphery of the filter element 5 is an inside seal part 13. The insideseal part 13 surrounds the inlet port 9 a in a rectangular ring shape.An inner region that is further on the inside than the inside seal part13 is a filtering region through which blood flows. A portion of thefilter element 5 that faces the filtering region is an effectivefiltering portion 5 a. In this connection, a protruding nonwoven fabricportion 5 c that is a surplus portion of the filter element 5 protrudesto the outside of the inside seal part 13 within the flexible container3. The inside seal part 13 corresponds to a first seal part.

On the outlet side of the filter element 5, that is, on the rear side ofthe filter element 5, a rectangular ring shaped recess is formed incorrespondence to the rectangular ring-shaped inside seal part 13 (seeFIG. 4). This recess is formed as a result of the filter element 5 beingsandwiched and compressed by the inlet-side container 9 and the flowchannel securing sheet 7 and being adhered in that state. This recess isa valley part 6 that is provided on the outlet side of the filterelement 5.

The peripheries of the inlet-side container 9 and the outlet-sidecontainer 11 are sealed together in a mutually overlapping manner so asto surround the inside seal part 13 in a ring shape at a position thatis closer to an outer edge than the inside seal part 13. The band-shapedbonding region in which the inlet-side container 9 and the outlet-sidecontainer 11 are directly bonded is an outside seal part 15. The outsideseal part 15 corresponds to a second seal part.

The flow channel securing sheet 7 is also sealed to the filter element 5at the inside seal part 13. Accordingly, a recess 7 a that is formed inthe same shape as the valley part 6 of the filter element 5 also arisesin the flow channel securing sheet 7. The outlet-side container 11 isnot bonded to the filter element 5 and the flow channel securing sheet7. In an at-rest state, the outlet-side container 11 is in a state inwhich the outlet-side container 11 is roughly separated from the valleypart 6 of the filter element 5 and the recess 7 a of the flow channelsecuring sheet 7. If a state is assumed in which blood is flowing (anegative pressure state), an empty space region (hereunder, referred toas a “passage region”) S is formed between the filter element 5 and theoutlet-side container 11 by the valley part 6 of the filter element 5and the recess 7 a of the flow channel securing sheet 7 (see FIG. 8).

The valley part 6 of the filter element 5 will now be described infurther detail referring to FIG. 5. FIG. 5 is a schematic view thatillustrates the filter element 5 in an at-rest state, that is, a statein which blood is not flowing. In particular, FIG. 5 is a view thatschematically illustrates the relationship between an area in which thevalley part 6 is formed and other areas. The valley part 6 includes abottom part 6 a that overlaps with the inside seal part 13, an innerslanted face portion 6 b that rises towards the inside of the insideseal part 13 from the bottom part 6 a, and an outer slanted face portion6 c that rises towards the outside of the inside seal part 13. The innerslanted face portion 6 b smoothly connects to a main region portion 8 onthe outlet side of the filter element 5. The outer slanted face portion6 c is a region that is formed by the protruding nonwoven fabric portion5 c.

Formation of the valley part 6 will now be described in detail. Alaminated filter element has a constant thickness, and the surface ofthe filter element is in a flat state when a process such as welding hasnot been performed. Subsequently, for example, if the two faces of thefilter element are sandwiched with a PVC sheet and high frequencywelding is performed, the welded place is crushed in the weldingprocess, and the welded place becomes thin in comparison to the originalthickness of the filter element. In this case, according to the filterelement 5 of the present embodiment, for example, high frequency weldingis carried out using a predetermined mold to form the inside seal part13, and as a result an annular welded place is formed. Although theplaces other than the welded place are substantially flat over theentire area of the filter element 5 after welding also, only thevicinity of the welded place is different, and when attention is focusedon the outlet side it can be seen that a place adjoining the weldedplace rises almost perpendicularly from the welded place and connects toa flat portion (main region portion 8) of the filter element 5. Morespecifically, the region corresponding to the welded place is the bottompart 6 a of the valley part 6, the region that rises almostperpendicularly towards the inner side from the bottom part 6 a is theinner slanted face portion 6 b, and the region that rises almostperpendicularly towards the outer side from the bottom part 6 a is theouter slanted face portion 6 c.

Next, the relationship between a face on the outlet side of the filterelement 5 on which the valley part 6 is formed (hereunder, referred toas “outlet-side nonwoven fabric surface”) and the outlet-side container11 is described. First, a cross section (hereunder, referred to as“hypothetical cross section”) that cuts the blood processing filter 1Aalong an arbitrary straight line that passes through approximately thecenter of the outlet-side nonwoven fabric surface is supposed. FIG. 5 isa view that schematically illustrates the hypothetical cross section.

In this case, a first line segment Sa that indicates the outlet-sidenonwoven fabric surface on the hypothetical cross section, and a secondline segment Sb that indicates a region which corresponds to theoutlet-side nonwoven fabric surface among the entire inner surface ofthe outlet-side container 11 on the hypothetical cross section arespecified. The first line segment Sa links both ends of the outlet-sidenonwoven fabric surface and is formed in the same shape as theoutlet-side nonwoven fabric surface. With respect to the second linesegment Sb, first, an orthogonal direction to the longitudinal directionof the filter element 5 on the hypothetical cross section is assumed tobe a corresponding direction, and a straight line that extends along therespective corresponding directions from both ends of the outlet-sidenonwoven fabric surface is assumed. Next, two points Pa and Pb at whichthe two straight lines intersect with the inner surface of theoutlet-side container 11 are specified. The two points Pa and Pbcorrespond to both ends of the outlet-side nonwoven fabric surface onthe inner surface of the outlet-side container 11. A line segment thatlinks the two points Pa and Pb in a manner that follows the shape of theinner surface of the outlet-side container 11 is the second line segmentSb.

Comparing the first line segment Sa and the second line segment Sb,since the valley part 6 is formed in the filter element 5, the firstline segment Sa is longer than the second line segment Sb. As a resultan empty space region is formed in the valley part 6 in an at-reststate. Further, with respect to the outlet-side container 11, althoughthe material thereof has some margin for expansion and contraction it isnot a material that expands by any amount, and since the first linesegment Sa is longer than the second line segment Sb, even if a state isentered in which blood flows and is attached thereto (is attached due toa negative pressure), the outlet-side container 11 does not contact thefilter element 5 in the vicinity of the inside seal part 13, inparticular in the vicinity of the bottom part 6 a of the valley part 6.As a result, the passage region S is formed which can be used as a flowchannel for blood.

As shown in FIGS. 1 to 4, the flow channel securing sheet 7 is arrangedso as to cover the effective filtering portion 5 a of the filter element5 on the outlet side of the filter element 5. A plurality of flowchannel holes 7 b are formed in a region facing the effective filteringportion 5 a of the flow channel securing sheet 7. The outlet port 11 aof the outlet-side container 11 is arranged so as to be capable ofcommunicating with a flow channel hole 7 b. In this connection, thestatement “the outlet port 11 a is arranged so as to be capable ofcommunicating with a flow channel hole 7 b” means that, when a state inwhich blood is flowing is assumed, or when blood is actually flowing, itis possible to form a continuous empty space which is not adheredbetween the outlet-side container 11 and another element, and forexample, includes a case in which the outlet port 11 a is arranged so asto overlap with the flow channel hole 7 b or the valley part 6 in anat-rest state, or a case in which, when blood is flowing, the outletport 11 a is arranged in the passage region S formed by the valley part6. According to the present embodiment, the outlet port 11 a is arrangedso as to overlap with the valley part 6 in an at-rest state. As aresult, in a state in which blood is flowing, a forms is realized inwhich a continuous empty space is formed from the outlet port 11 a tothe passage region S.

With respect to all of the plurality of flow channel holes 7 b formed inthe flow channel securing sheet 7, at least a portion of the flowchannel holes 7 b is arranged over the inner slanted face portion 6 b.Further, when a state in which blood is flowing is assumed, a state isentered in which at least a portion of the flow channel holes 7 b isarranged in the passage region S as described later. As a result, therespective flow channel holes 7 b connect to each other so that bloodcan freely enter and leave through the passage region S in a state inwhich blood is flowing, and thus the inflow and outflow of blood arestably maintained (see FIG. 6).

Specifically, the plurality of flow channel holes 7 b are formed in theflow channel securing sheet 7 by partially cutting out the sheet. Eachflow channel hole 7 b is formed in a slit shape that is long along thelongitudinal direction of the flow channel securing sheet 7. Hereunder,the slit-shaped flow channel holes 7 b are also referred to as “slitportions”. The plurality of slit portions 7 b and sheet portions thatremain between adjoining slit portions 7 b are arranged so as to facethe effective filtering portion 5 a. Preferably, in the flow channelsecuring sheet 7, the proportion of the gross area of the slit portions(flow channel holes) 7 b with respect to the area of the effectivefiltering portion 5 a of the filter element 5 is between 30% and 99%.

Two ends 7 c of the slit portions 7 b extend as far as the vicinity ofthe inside seal part 13. As a result, the two ends 7 c of the slitportions 7 b are arranged over the inner slanted face portion 6 b of thevalley part 6. Further, when a state in which blood is flowing isassumed, a state is entered in which the two ends 7 c of the slitportions 7 b are arranged in the passage region S. By at least oneportion of the slit portions 7 b being arranged in the passage region S,a state is entered in which the inside of the slit portions 7 b and theinside of the passage region S communicate, and thus a blood flowchannel is formed.

From the viewpoint of stably maintaining the blood flow, it does notmatter how close the ends 7 c of the slit portions 7 b are to the insideseal part 13, that is, it does not matter how large an area is in whichat least one portion of the slit portions 7 b is arranged in the passageregion S. However, if a portion of the slit portion 7 b rests on(overlaps with) the inside seal part 13, the slit portion 7 b may hinderformation of the inside seal part 13. Therefore, it is good for adistance d (see FIG. 4) between the end 7 c of each slit portion 7 b andan inside end of the inside seal part 13 to be between 0.1 mm and 3 mm,preferably between 0.3 mm and 2 mm, and more preferably between 0.5 mmand 1.5 mm.

The size of the slit portions 7 b can be decided in various ways. Fromthe viewpoint of blood flow, the larger the gross area of the slitportions 7 b is, the larger the size of a blood flow channel that can besecured will be. However, if each individual slit portion 7 b is toolarge, there is a concern that the filter element 5 and the outlet-sidecontainer 11 will contact inside the slit portions 7 b due todeformation of the outlet-side container 11 that is caused by a negativepressure, and that the blood flow channel will be blocked. Accordingly,it is preferable that the width of each slit portion 7 b is such thatblockage of the flow channel does not occur. For example, although thewidth will also be influenced by the softness of the outlet-sidecontainer 11 that depends on the material and thickness and the like ofthe outlet-side container 11, it is good for the width of the slitportions 7 b to be between 0.5 mm and 20 mm, preferably between 1 mm and15 mm, and more preferably between 1 mm and 10 mm.

An interval between one slit portion 7 b and another slit portion 7 b isnot particularly limited as long as it is possible to maintain the shapeof the slit portions 7 b during the manufacturing process, during use ofthe blood processing filter 1A, and during the transportation process,and to also obtain an adequate strength. The smaller a value is for theinterval between the slit portions 7 b, the larger the gross area of theslit portions 7 b can be.

Normally, a thickness t of the flow channel securing sheet 7 can besubstantially the same as that of the flexible container 3. Even if thewidth of the slit portions 7 b is the same, the greater the thickness ofthe flow channel securing sheet 7 is, the greater the size of the flowchannel that can be secured, and the greater the decrease in the risk ofthe flow channel being blocked due to deformation of the outlet-sidecontainer 11. However, as the thickness of the flow channel securingsheet 7 increases, the greater a qualitative increase in a loss amountbecomes due to an increase in the space inside the slit portions 7 b. Athickness between 0.1 mm and 3 mm is good as the thickness t of the flowchannel securing sheet 7, and preferably the thickness t is between 0.2mm and 2 mm, and more preferably between 0.2 mm and 1.5 mm.

The inlet port 9 a that is sealed in the inlet-side container 9 can beappropriately arranged in a region on the inside of the inside seal part13. The inlet port 9 a according to the present embodiment is arrangedat one end side in the longitudinal direction of the flexible container3, that is, on the upper side in a state in which the blood processingfilter 1A is placed upright for blood processing. An inlet flow channel9 b that accepts pre-processing blood when an inlet-side circuit 102(see FIG. 7) through which blood flows is formed, is formed in the inletport 9 a. An inlet opening 9 c is formed in the inlet port 9 a. Theinlet opening 9 c allows the inlet flow channel 9 b and the inside ofthe inlet-side container 9 to communicate.

The outlet port 11 a that is sealed in the outlet-side container 11 canbe appropriately arranged in a region on the inside of the outside sealpart 15. The outlet port 11 a according to the present embodiment isarranged at the other end side in the longitudinal direction of theflexible container 3, that is, on the lower side in a state in which theblood processing filter 1A is placed upright for blood processing. Anoutlet flow channel 11 b that discharges blood that is processed by thefilter element 5 when an outlet-side circuit 104 (see FIG. 7) throughwhich blood flows is formed, is formed in the outlet port 11 a.

An outlet opening 11 c is formed in the outlet port 11 a. The outletopening 11 c allows the inside of the outlet-side container 11 and theoutlet flow channel 11 b to communicate. At least one portion of theoutlet opening 11 c of the outlet port 11 a is arranged so as to overlapin a planar view with the slit portions 7 b of the flow channel securingsheet 7. By arranging the outlet opening 11 c so that at least oneportion thereof overlaps with the slit portions 7 b, blood flowsefficiently and the filter element 5 as a filter material can beeffectively utilized.

Specifically, in a state in which blood is flowing, a negative pressurearises on the outlet side of the filter element 5 and a force acts onthe outlet-side container 11 to cause the outlet-side container 11 tostick to the filter element S side. However, on the outlet side of thefilter element 5, the valley part 6 is recessed with respect to the mainregion portion 8 (see FIG. 5) and, in addition, the outer slanted faceportion 6 c (protruding nonwoven fabric portion 5 c) of the valley part6 interferes with the outlet-side container 11 so that adherence to theflow channel securing sheet 7 or the filter element 5 is restricted, andtherefore an empty space region (passage region) S is formed by thevalley part 6 between the filter element 5 and the outlet-side container11. One part of the slit portions 7 b of the flow channel securing sheet7 is arranged over the inner slanted face portion 6 b of the valley part6. In a state in which blood is flowing, the slit portions 7 b connectas a blood flow channel to the passage region S, and furthermore thisblood flow channel and the outlet opening 11 c of the outlet port 11 aare connected as a blood flow channel. As a result, blood processed bythe filter element 5 can be efficiently discharged to outside the bloodprocessing filter 1A, and at the same time the possibility of the outletopening 11 c being blocked by the filter element 5 can be avoided.

In this connection, although at least one portion of the outlet opening11 c according to the present embodiment is arranged so as to overlapwith the slit portions 7 b, a form may also be adopted in which asimilar effect is obtained by arranging at least one portion of theoutlet opening 11 c so as to overlap with the passage region S in aplanar view.

According to the blood processing filter 1A as described above, theoutlet-side container 11 is not included in the inside seal part 13. Asa result, the passage region S is formed by the valley part 6 of thefilter element 5, and the passage region S is utilized as a blood flowchannel. The slit portions (flow channel holes) 7 b of the flow channelsecuring sheet 7 connect as a blood flow channel to the passage region Sthat surrounds the effective filtering portion 5 a of the filter element5, and discharge blood to the outlet port 11 a.

That is, on the outlet side, the flow of blood that flows out from thefilter element 5 to the inside seal part 13 that is a blood flow channeldoes not concentrate at one point (the outlet opening 11 c) whilepassing through an extremely narrow gap where the outlet-side container11 and the filter element 5 are adhered, but rather passes through ablood flow channel formed by the slit portions 7 b and the like.Further, since at least one portion of the outlet opening 11 c of theoutlet port 11 a is arranged so as to overlap at least one of thepassage region S and the slit portions 7 b, a state is entered in whichthe blood flow channel and the outlet port 11 a are connected, and thusblood can be efficiently discharged to outside, and at the same time therisk of the outlet opening 11 c being blocked by the filter element 5can be eliminated.

Next, forms of the material and shape and the like of each elementconstituting the blood processing filter 1A are described. As describedin the foregoing, the flexible container 3 is formed by the inlet-sidecontainer 9 and the outlet-side container 11. Any material that iscommercially available as a sheet or a film can be used as a flexibleresin that is used for the flexible container 3. For example,thermoplastic elastomers such as soft polyvinyl chloride, polyurethane,ethylene-vinyl acetate copolymer, polyolefin such as polyethylene andpolypropylene, hydrogenated styrene-butadiene-styrene copolymer,styrene-isoprene-styrene copolymer, and hydrogenated products thereof,mixtures of the thermoplastic elastomer and a softening agent such aspolyolefin and ethylene-ethyl acrylate; and the like may be mentioned asfavorable materials. Since it can be considered that the material willcontact with blood, preferable materials are soft polyvinyl chloride,polyurethane, and polyolefin that are used as the material of medicalproducts such as blood bags, as well as thermoplastic elastomerscontaining these materials as main components, and more preferably thematerial is soft polyvinyl chloride.

Further, for example, a container described in Japanese Patent Laid-OpenNo. 7-267871 or a container described in International Publication No.WO 95/017236 can also be used as the flexible container 3.

The filter element 5 is manufactured using a filter material constitutedby a fibrous integrated body such as nonwoven fabric or woven fabric orby a porous body such as sponge. The filter element 5 according to thepresent embodiment may be coated with a hydrophilic polymer to make iteasier for blood to wet the filter material. Further, to facilitateattachment of leukocytes to the filter element 5 when using the bloodprocessing filter 1A to remove leukocytes from blood, a filter materialthat is coated with a polymer may be used.

The flow channel securing sheet 7 can be manufactured using the samematerial as the flexible container 3, and the slit portions 7 b can beappropriately manufactured by a punching process or other method. Inthis connection, according to the present embodiment, the slit portions7 b are exemplified as the flow channel holes 7 b, and a form isdescribed in which the two ends 7 c thereof are arranged over the innerslanted face portion 6 b of the valley part 6, and furthermore, the slitportions 7 b are arranged in the passage region S formed by the valleypart 6 when blood is flowing. However, the flow channel holes can take avariety of forms as long as one portion thereof is arranged in thepassage region S. For example, with respect to a rectangular flowchannel securing sheet 7 that is vertically long, the flow channel holes7 b may have a shape that is long in the vertical direction as in thepresent embodiment, or the flow channel holes may be long from side toside, or the flow channel holes may be a helical shape.

Further, according to the present embodiment, a form is described inwhich the plurality of flow channel holes 7 b have substantially thesame shape. However, the shapes and sizes of the plurality of flowchannel holes need not necessarily be the same. For example, the flowchannel holes may include both flow channel holes that are long in thevertical direction and flow channel holes that are long from side toside, and the width dimensions of the flow channel holes may bedifferent to each other. Furthermore, flow channel holes of variousshapes and dimensions may be arranged in an orderly arrangement or arandom arrangement.

In addition, a configuration can be adopted in which a single flowchannel hole is formed as a result of linking a plurality of slit-shapedholes to each other, and one portion thereof is linked to the outletopening 11 c. In particular, according to this configuration, asufficient flow of blood can be secured even if a portion of the flowchannel hole is not connected to the passage region S that is formed bythe valley part 6 in a state in which blood is flowing. In this case,the fact that the slit-shaped holes are linked to each other means thatsheet portions of the slit-shaped holes are in a cut state. Accordingly,the utmost care is required to ensure that the sheet portion of the flowchannel securing sheet 7 does not break during the process ofmanufacturing the blood processing filter 1A. If that problem can beavoided, a function as the flow channel securing sheet 7 can beobtained.

Next, a method for manufacturing the blood processing filter 1Aaccording to the present embodiment is described. According to thismanufacturing method, for example, the inlet-side container 9 in whichthe inlet port 9 a has been sealed at a predetermined position, theoutlet-side container 11 in which the outlet port 11 a has been sealedat a predetermined position, the filter element 5, and the flow channelsecuring sheet 7 are prepared, and an installing step is performed inwhich the inlet-side container 9 and the outlet-side container 11 arearranged so as to sandwich the filter element 5 and, further, the flowchannel securing sheet 7 is arranged between the filter element 5 andthe outlet-side container 11. In this case, the flow channel holes 7 bthrough which blood that is processed by the filter element 5 passes areformed in the flow channel securing sheet 7, and the outlet port 11 a isarranged at a predetermined position so as to be capable ofcommunicating with the flow channel holes 7 b.

Further, in the installing step, the flow channel securing sheet 7 isarranged at a predetermined position so that, when a state in whichblood is flowing is assumed, at least one portion of the flow channelholes 7 b formed in the flow channel securing sheet 7 is arranged in theempty space region (passage region) S that is formed by the valley part6. In addition, the outlet opening 11 c that communicates with theinside of the outlet-side container 11 is formed in the outlet port 11a, and at least one portion of the outlet opening 11 c is arranged so asto overlap with at least one of the valley part 6 and the flow channelholes 7 b.

Next, a sealing step is performed in which the inlet-side container 9and the outlet-side container 11 are sealed in a state in which theinlet-side container 9 and the outlet-side container 11 sandwich thefilter element 5 and the flow channel securing sheet 7 that have beenarranged at predetermined positions in the installing step. The sealingstep includes a first sealing step and a second sealing step. In thefirst sealing step, the inside seal part 13 is formed by sealing theinlet-side container 9, the filter element 5, and the flow channelsecuring sheet 7 in a band shape so as to surround the area in which theinlet port 9 a is formed without adhering the filter element 5 and theoutlet-side container 11. In the second sealing step, an annular outsideseal part 15 is formed at a position that is closer to an outer edgethan the inside seal part 13. The outside seal part 15 is formed bysealing so as to surround the inside seal part 13.

In the first sealing step, the valley part 6 that has a band shape thatcorresponds to the inside seal part 13 is generated on the outlet sideof the filter element 5. In a state in which blood is flowing, thepassage region S is formed between the outlet-side container 11 and thefilter element 5 by the valley part 6.

Although formation of the inside seal part 13 in the first sealing step,more specifically, sealing of the inlet-side container 9, the filterelement 5, and the flow channel securing sheet 7 can be performedutilizing high frequency welding, the present invention is not limitedthereto, and any kind of bonding technique, such as ultrasonic weldingor thermal welding, can be used. Preferably, the material used for theflow channel securing sheet 7 is the same as that used for theinlet-side container 9.

Likewise, although formation of the outside seal part 15 in the secondsealing step, more specifically, sealing of the inlet-side container 9and the outlet-side container 11 can be performed utilizing highfrequency welding, the present invention is not limited thereto, and anykind of bonding technique, such as ultrasonic welding or thermalwelding, can be used.

According to the above described manufacturing method, a form isdescribed in which the inlet port 9 a and the outlet port 11 a arepreviously sealed to the flexible container 3. However, sealing may beperformed after forming the inside seal part 13 or the outside seal part15, or may be performed during the process of forming the inside sealpart 13 or the outside seal part 15. Further, a method of sealing theinlet port 9 a as a blood inlet and the outlet port 11 a as a bloodoutlet to the flexible container 3 is not limited to high frequencywelding, and any kind of bonding technique, such as thermal welding, canbe used. Similarly to the flexible container 3, various known materialscan be used as the material of the inlet port 9 a and the outlet port 11a.

According to the above described manufacturing method, since theoutlet-side container 11 is not included in the inside seal part 13,that is, since the outlet-side container 11 is not sealed to the filterelement 5 and the flow channel securing sheet 7, there is the advantagethat arrangement of the outlet port 11 a in the step of sealing theoutlet port 11 a to the outlet-side container 11 can be performed with acomparatively high degree of freedom. More specifically, althoughsealing the inlet port 9 a or the outlet port 11 a inside the flexiblecontainer 3 is an advantage of the process of manufacturing thecontainer welding type blood processing filter 1A in which forming theinside seal part 13 or the outside seal part 15 by a simple step is afeature, by adopting a configuration in which the inside seal part 13does not seal the outlet-side container 11 it is possible to provide aneven greater degree of freedom with respect to arrangement of the outletport 11 a. As a result, an optimal arrangement of elements in which theoutlet port 11 a overlaps with the flow channel holes 7 b of the flowchannel securing sheet 7 or the passage region S formed by the valleypart 6 of the filter element 5 is facilitated.

Next, a blood processing system 100 that includes the blood processingfilter 1A according to the first embodiment and a usage state (state inwhich blood is flowing) of the blood processing filter 1A is describedreferring to FIG. 7 and FIG. 8. FIG. 7 is a front view that illustratesan outline of a blood processing system. FIG. 8 is a sectional view thatillustrates a state when the blood processing filter is being used.

The blood processing filter 1A can be used for filtering using gravity.For example, the blood processing system 100 to which the bloodprocessing filter 1A is applied includes a reservoir bag 101 into whichblood is filled after collection, the blood processing filter 1A, and arecovery bag 103 for accumulating blood after filtering. The reservoirbag 101 and the inlet port 9 a of the blood processing filter 1A areconnected to each other by a capillary tube 102 a such as a blood tube.The recovery bag 103 and the outlet port 11 a of the blood processingfilter 1A are connected to each other by a capillary tube 104 a such asa blood tube. Further, opening/closing means 102 b such as a rollerclamp that opens and closes a flow channel and a chamber 102 c and thelike is mounted in the capillary tube 102 a on the upstream side. Theinlet-side circuit 102 is formed by the capillary tube 102 a, theopening/closing means 102 b, and the chamber 102 c and the like. Theoutlet-side circuit 104 is formed by the capillary tube 104 a and thelike on the downstream side.

The reservoir bag 101 into which blood is filled after collection isarranged at a position that is approximately 50 cm higher than the bloodprocessing filter 1A. The recovery bag 103 in which blood is accumulatedafter filtering is arranged at a position that is approximately 100 cmlower than the blood processing filter 1A. A blood filtering process isperformed by opening the flow channel of the blood processing system100. When a filtering process is performed (at a time of use), anegative pressure arises on the outlet side of the flexible container 3of the blood processing filter 1A, and the outlet-side container 11deforms and attempts to adhere to the filter element 5. However, sincethe valley part 6 is formed on the outlet side of the filter element 5,and the recess 7 a that is the same shape as the valley part 6 is alsoformed in the flow channel securing sheet 7, the passage region S thatserves as a blood flow channel is formed between the filter element 5and the outlet-side container 11 by the valley part 6 of the filterelement 5 and the recess 7 a of the flow channel securing sheet 7.Further, since one portion of the slit portions 7 b of the flow channelsecuring sheet 7 is arranged in the passage region S, and the passageregion S connects to the outlet port 11 a, the blood flow channel fromthe slit portions 7 b to the outlet port 11 a is stably maintainedwithout being blocked.

Next, the actions and effects of the blood processing filter 1Aaccording to the present embodiment are described. According to theblood processing filter 1A, even if a dual force caused by a positivepressure on the inlet side and a negative pressure on the outlet sideacts at the time of filtering, the flow of blood is ensured between theflow channel holes 7 b of the flow channel securing sheet 7 and theoutlet port 11 a. Accordingly, it is possible to avoid a situation inwhich the flow of blood is inhibited by adherence or the like betweenthe outlet-side container 11 and the filter element 5 of the bloodprocessing filter 1A and filtering performance is lowered. This isadvantageous in terms of effectively utilizing the entire filter element5, and thus both a high filtering flow rate and high filteringperformance can be achieved in a compatible manner.

Particularly, according to the blood processing filter 1A of the presentembodiment, since at least one portion of the flow channel holes 7 bformed in the flow channel securing sheet 7 is arranged over the innerslanted face portion 6 b of the valley part 6, and is arranged in thepassage region S formed by the valley part 6 in a state in which bloodis flowing, all of the plurality of flow channel holes 7 b are linkedthrough the passage region S, and thus a drop in filtering performanceaccompanying blockage of the blood flow channel can be suppressed.

In addition, according to the blood processing filter 1A of the presentembodiment, since at least one portion of the outlet opening 11 c of theoutlet port 11 a is arranged so as to overlap with at least one of thepassage region S and the flow channel holes 7 b, after blood isprocessed by the filter element 5, the blood can be efficientlydischarged to outside of the blood processing filter 1A, and at the sametime the possibility that the outlet opening 11 c will be blocked by thefilter element 5 can also be avoided.

Further, according to the blood processing filter 1A of the presentembodiment, the outlet-side container 11 is not included in the insideseal part 13. It is therefore possible to prevent a situation in whichthe filter element 5 in the vicinity of the inside seal part 13 issandwiched by the flexible container 3 and the flow of blood isinhibited. Moreover, since the passage region S is formed by the valleypart 6 corresponding to the inside seal part 13, and the passage regionS can be utilized as a blood flow channel, it is possible to efficientlyutilize the filter material at a peripheral portion of the filterelement 5 in the vicinity of the inside seal part 13, at which,conventionally, blood tends to flow with difficulty.

Next, the advantages of the blood processing filter 1A and the methodfor manufacturing the blood processing filter 1A of the presentembodiment are summarized. According to the blood processing filter 1A,the flow channel securing sheet 7 can be assembled inside the flexiblecontainer 3, and the flow channel holes 7 b of the flow channel securingsheet 7 and the outlet port 11 a can be connected and utilized as ablood flow channel without leading to the risk of a welding defect,complicating the manufacturing process, or increasing costs. As aresult, a situation in which the flow of blood is inhibited andfiltering performance declines can be avoided, more complete priming andair bleeding can be realized, the entire filter element 5 can beeffectively utilized, and a high flow rate and high filteringperformance can be simultaneously achieved. Further, the bloodprocessing filter 1A that provides such advantages can be manufactured.

Next, a blood processing filter according to a second embodiment of thepresent invention is described referring to FIG. 9. FIG. 9 is asectional view that illustrates, in an enlarged manner, an end of a flowchannel hole of a flow channel securing sheet and an inside seal part ofa blood processing filter according to the second embodiment of thepresent invention. In this connection, in FIG. 9 an at-rest state isindicated by a solid line, and a state in which blood is flowing (anegative pressure state) is indicated by a chain double-dashed line. Ablood processing filter 1B according to the second embodiment includessubstantially the same elements and structures as the blood processingfilter 1A according to the first embodiment. Hence, elements andstructures that are the same as in the first embodiment are denoted bythe same reference symbols and a detailed description thereof isomitted, and the following description centers on elements andstructures that are different from those of the first embodiment.

The blood processing filter 1B includes a flexible container 3 that hasan inlet port 9 a and an outlet port 11 a for blood, a sheet-like filterelement 5 that is arranged so as to divide the inside of the flexiblecontainer 3 into an inlet port 9 a side and an outlet port 11 a side,and a flow channel securing sheet 21 that is arranged so as to overlapwith the filter element 5. The flexible container 3 includes aninlet-side container 9 having a rectangular sheet shape, and anoutlet-side container 11 having a rectangular sheet shape.

The inlet-side container 9 and the outlet-side container 11 overlap witheach other through the rectangular filter element 5 and the rectangularflow channel securing sheet 21. The inlet-side container 9, the filterelement 5, and the flow channel securing sheet 21 are sealed in closecontact with each other, and as a result a band-shaped inside seal part13 is formed along the periphery of the filter element 5.

The flow channel securing sheet 21 is arranged on the rear side of thefilter element 5 so as to cover an effective filtering portion 5 a ofthe filter element 5. A plurality of flow channel holes 21 h are formedin a region facing the effective filtering portion 5 a of the flowchannel securing sheet 21, and at least one portion of all of the flowchannel holes 21 b is arranged over an inner slanted face portion 6 b ofa valley part 6. In a state in which blood is flowing, a passage regionS is formed by the valley part 6 between the filter element 5 and theoutlet-side container 11, and since one portion of the flow channelholes 21 b is arranged in the passage region S, the flow channel holes21 b communicate with each other through the passage region S to therebystably maintain the inflow and outflow of blood.

The area of the flow channel securing sheet 21 according to the presentembodiment is wider than the area of the flow channel securing sheet 7of the first embodiment. The flow channel securing sheet 21 is clampedand adhered between the periphery of the inlet-side container 9 and theperiphery of the outlet-side container 11. That is, the inlet-sidecontainer 9, the flow channel securing sheet 21, and the outlet-sidecontainer 11 are sealed at a position that is closer to an outer edgethan the inside seal part (first seal part) 13 to thereby form anoutside seal part (second seal part) 15. Consequently, a sealing step ofa method for manufacturing the blood processing filter 1B according tothe present embodiment includes a first sealing step of sandwiching andadhering the filter element 5 between the inlet-side container 9 and theflow channel securing sheet 21, and a second sealing step of sandwichingand adhering the flow channel securing sheet 21 between the inlet-sidecontainer 9 and the outlet-side container 11.

Further, an outlet port 11 g of the present embodiment is arranged at aposition that is on an upper side of the blood processing filter 1B in astate in which the blood processing filter 1B is upright to performblood processing, more specifically, at a position that is above theinlet port 9 a when filtration is performed by means of a gravity drop,and in particular at a position in the vicinity of the passage region Sthat is the uppermost part thereof. At least one portion of the outletopening 11 h is arranged so as to overlap with the passage region S.

By adopting a configuration in which the outlet port 11 g is arranged asdescribed above, the blood processing filter 1B is filled with bloodfrom the bottom upwards at a time of priming at the start of bloodprocessing. As a result, since air can easily exit from the outlet port11 g that is arranged at the upper part of the blood processing filter1B, more complete priming and air bleeding can be performed without theneed to pay attention to a gravity drop setting or a flow rate at thetime of priming. Thus, the filter element 5 can be utilized moreeffectively as a filter material, and a higher flow rate and higherfiltering performance can be obtained. At such time, since the entireblood processing filter 1B swells because blood does not flow to outsidethe blood processing filter 1B until priming is completed, at firstglance it seems that priming of the blood processing filter 1B requirestime. However, in fact, after priming ends the blood accumulated on theoutlet side is discharged to outside of the blood processing filter 1Bat one time by the force of gravity, and since the filter material isutilized more effectively by the more complete priming, the overall timerequired for the entire blood processing can be shortened.

According to the blood processing filter 1B of the present embodiment,even if a dual force generated by a positive pressure on the inlet sideand a negative pressure on the outlet side acts at the time offiltering, the flow of blood is ensured between the flow channel holes21 b of the flow channel securing sheet 21 and the outlet port 11 g.Accordingly, it is possible to avoid a situation in which the blood flowis inhibited by adherence or the like between the outlet-side container11 and the filter element 5 of the blood processing filter 1B andfiltering performance is lowered. This is advantageous in terms ofeffectively utilizing the entire filter element 5, and thus both a highfiltering flow rate and high filtering performance can be achieved in acompatible manner.

According to the blood processing filter 1B, since the flow channelsecuring sheet 21 spreads so as to continue as far as the outside sealpart 15, soakage of blood into the protruding nonwoven fabric portion 5c and loss of blood can be suppressed.

Next, a blood processing filter according to a third embodiment of thepresent invention is described referring to FIG. 10. FIG. 10 is a planview that illustrates one portion of the blood processing filteraccording to the third embodiment, that is shown in cut-away manner. Ablood processing filter 1C according to the third embodiment includessubstantially the same elements and structures as the blood processingfilter 1A according to the first embodiment. Hence, elements andstructures that are the same as in the first embodiment are denoted bythe same reference symbols and a detailed description thereof isomitted, and the following description centers on elements andstructures that are different from those of the first embodiment.

In the blood processing filter 1C according to the present embodiment,an outside seal part is not formed, and only an inside seal part 13 thatclamps a filter element 5 and a flow channel securing sheet 7 in arectangular ring shape is formed between an inlet-side container 9 andan outlet-side container 11. In the inlet-side container 9, an inletport 9 a is sealed in a region that is surrounded by the inside sealpart 13. In the outlet-side container 11, an outlet port 11 a is sealedin a region that is surrounded by the inside seal part 13. At least oneportion of an outlet opening 11 c of the outlet port 11 a is arranged soas to overlap with flow channel holes 7 b of the flow channel securingsheet 7, and thus a form in which the outlet port 11 a is capable ofcommunicating with the flow channel holes 7 b is realized. According tothe present embodiment, since the flow channel holes 7 b and the outletopening 11 c are connected as a blood flow channel, it is possible toavoid a situation in which the flow of blood is inhibited by adherenceor the like between the outlet-side container 11 and the filter element5 and filtering performance is lowered. This is advantageous in terms ofeffectively utilizing the entire filter element 5, and thus both a highfiltering flow rate and high filtering performance can be achieved in acompatible manner.

Next, a blood processing filter according to a fourth embodiment of thepresent invention is described referring to FIG. 11. FIG. 11 is asectional view of the blood processing filter according to the fourthembodiment, which shows the blood processing filter in an at-rest state.A blood processing filter 1D according to the fourth embodiment includessubstantially the same elements and structures as the blood processingfilter 1A according to the first embodiment and the blood processingfilter 1B according to the second embodiment. Hence, elements andstructures that are the same as in the first or second embodiment aredenoted by the same reference symbols and a detailed description thereofis omitted, and the following description centers on elements andstructures that are different from those of the first or secondembodiment.

The blood processing filter 1D includes a flexible container 31 havingan inlet port 9 a and an outlet port 11 a for blood, a sheet-like filterelement 5 that is arranged so as to divide the inside of the flexiblecontainer 31 into an inlet port 9 a side and an outlet port 11 a side, aflow channel securing sheet 34 that is arranged so as to overlap withthe filter element 5 on the outlet side of the filter element 5, and awelding frame sheet 35 that is arranged so as to overlap with the filterelement 5 on the inlet side of the filter element 5. The flexiblecontainer 31 includes an inlet-side container 32 having a rectangularsheet shape, and an outlet-side container 33 having a rectangular sheetshape.

The welding frame sheet 35 and the flow channel securing sheet 34overlap with each other so as to sandwich the rectangular filter element5. The welding frame sheet 35 and the flow channel securing sheet 34clamp the filter element 5 along the periphery of the filter element 5.The area at which the filter element 5 is clamped is sealed in a bandshape to form an annular inside seal part (first seal part) 36. That is,according to the present embodiment, instead of the inlet-side container32, the welding frame sheet 35 is welded to and integrated with thefilter element 5 and the flow channel securing sheet 34, and as a resultthe inside seal part 36 is formed. Further, according to the presentembodiment, a valley part 6 is formed on the outlet side of the filterelement 5 by the inside seal part 36.

In the welding frame sheet 35, a rectangular opening 37 that exposes asurface on the inlet side of the filter element 5 is formed on an innerside that is surrounded by the inside seal part 36. In this connection,although in the welding frame sheet 35 according to the presentembodiment a single opening 37 is provided in a shape that is formed bycutting out all of the inner side that is surrounded by the inside sealpart 36, a configuration may also be adopted in which one or a pluralityof openings are formed by adopting a shape in which one portion of theinner side that is surrounded by the inside seal part 36 remains.

The inlet-side container 32 and the outlet-side container 33 overlapwith each other through the welding frame sheet 35, the filter element5, and the flow channel securing sheet 34. The peripheries of theinlet-side container 32 and the outlet-side container 33 overlap withthe peripheries of the welding frame sheet 35 and the flow channelsecuring sheet 34 and are sealed in a band shape to thereby form anannular outside seal part (second seal part) 38.

According to the present embodiment, the peripheries of the weldingframe sheet 35 and the flow channel securing sheet 34 are clamped by theinlet-side container 32 and the outlet-side container 33, and are sealedand integrated. However, the welding frame sheet 35 may be a small sizethat is of a degree that enables the formation of the inside seal part36. Further, the flow channel securing sheet 34 and the welding framesheet 35 can be manufactured using the same material as the flexiblecontainer 3.

Similarly to the flow channel securing sheet 21 according to the secondembodiment, a plurality of flow channel holes 21 b are formed in theflow channel securing sheet 34, and at least one portion of all of theflow channel holes 21 b is arranged over an inner slanted face portion 6b of the valley part 6. In a state in which blood is flowing, a passageregion (empty space region) S is formed by the valley part 6 between thefilter element 5 and the outlet-side container 33, and since one portionof the flow channel holes 21 b is arranged inside the passage region S,the flow channel holes 21 b communicate with each other through thepassage region S so that the inflow and outflow of blood are stablymaintained.

According to the blood processing filter 1D of the present embodiment,even if a dual force generated by a positive pressure on the inlet sideand a negative pressure on the outlet side acts at the time offiltering, the flow of blood is ensured between the flow channel holes21 b of the flow channel securing sheet 34 and the outlet port 11 a.Accordingly, it is possible to avoid a situation in which the flow ofblood is inhibited by adherence or the like between the outlet-sidecontainer 33 and the filter element 5 of the blood processing filter 1Dand filtering performance is lowered. This is advantageous in terms ofeffectively utilizing the entire filter element 5, and thus both a highfiltering flow rate and high filtering performance can be achieved in acompatible manner.

EXAMPLES

The present invention will now be described in further detail below byway of examples. However, the following examples should not be construedas limiting the present invention.

Example 1

A filter including an inlet-side container (inlet-side flexiblecontainer), an outlet-side container (outlet-side flexible container), afilter element and a flow channel securing sheet was prepared, and aninlet port thereof was connected to a pre-filtration liquid reservoirbag via an inlet-side circuit having a length of 50 cm. An outlet portof the filter was connected to a post-filtration liquid recovery bag viaan outlet-side circuit having a length of 100 cm. A tube made of softpolyvinyl chloride having an internal diameter of 2.9 mm and an externaldiameter of 4.2 mm was used for the inlet-side circuit and theoutlet-side circuit.

In preparing the filter, an effective filtering portion was formed in arectangular shape in which an inner side of an inside seal part (firstseal part) had a longitudinal dimension of 74 cm and a horizontaldimension of 57 cm, a corner portion was formed as a curve, and aneffective filtration area of 42×10⁻⁴ (m²) was provided. As the filterelement, four sheets of polyester nonwoven fabric having an airpermeability of 237.3 (cc/cm²/sec) and a thickness of 0.2 mm, one sheetof polyester nonwoven fabric having an air permeability of 8.4(cc/cm²/sec) and a thickness of 0.4 mm, 32 sheets of polyester nonwovenfabric having an air permeability of 7.7 (cc/cm²/sec) and a thickness of0.20 mm, one sheet of nonwoven polyester fabric having an airpermeability of 8.4 (cc/cm²/sec) and a thickness of 0.4 mm, and foursheets of nonwoven polyester fabric having an air permeability of 237.3(cc/cm²/sec) and a thickness of 0.2 mm were stacked in that order froman inlet to an outlet at the time of filtering blood, and used. In thisconnection, the air permeability was measured by a method based onJapanese Industrial Standard JIS L-1096, 6.27.1A. The flow channelsecuring sheet was sealed at the same time as the first seal part wasformed. The size of flow channel securing sheet was made larger than theentire external side of the first seal part and smaller than thelaminated filter element. Similarly to the flexible container, aflexible sheet having a thickness of 0.4 mm was used for the flowchannel securing sheet, and 11 slit portions with a length of 72 mm anda width of 3 mm were formed at portions that were further on the insidethan the first seal part by cutting out the sheet. At that time, theslit portions were formed such that the positions thereof in thevertical direction were aligned and intervals between the slit portionsin the width direction were 2 mm, so that the slit portions weresymmetrical when viewed from the center of the first seal part.

The inlet port and the outlet port were sealed to the inlet-sideflexible container and the outlet-side flexible container, respectively.The outside seal part (first seal part) was formed by disposing theinlet-side flexible container and the flow channel securing sheet in alayered arrangement so as to sandwich the filter element therebetween,and thereafter the second seal part was formed by overlaying theoutlet-side flexible container on the opposite side of the inlet-sideflexible container. At that time, sealing and assembly were performed soas to provide an inlet opening for allowing blood to flow out from theinlet port to inside the flexible container at a position that was 2.4cm below an end on the effective filtering portion side of the uppermostportion of the first seal part. Further, sealing and assembly wereperformed so as to provide an outlet opening for allowing bloodprocessed by the filter element to flow out to an outlet flow channelinside the outlet port at a position that was 2.4 cm above an end on theeffective filtering portion side of the lowermost portion of the firstseal part. Assembly was performed so as to arrange the outlet opening ofthe outlet port in the center in the width direction of the inner sideof the first seal part, and so that one portion of the outlet openingoverlapped with a central slit portion among the plurality of slitportions of the flow channel securing sheet.

The total of the upstream side drop, the drop between the inlet andoutlet of the blood processing filter, and the downstream side drop wasfixed at 150 cm. Thereafter, as a liquid to be processed (a bloodsubstitute), 300 g of an aqueous solution of polyvinyl pyrrolidone(molecular weight: 360,000) adjusted to a viscosity of 17 mPa·s (25° C.)and pH 3.8 was filled into a pre-filtration liquid reservoir bag, andcaused to flow at room temperature using gravity. A post-filtrationliquid recovery bag was placed in advance on a scale balance to enableverification of changes in the weight thereof.

At this time, the time required from when the liquid to be processedstarted to flow until the liquid first reached the inlet of thepost-filtration liquid recovery bag was measured, and the measured timewas defined as a priming time (minutes). Further, a time required fromwhen the liquid to be processed started to flow until all of the liquidto be processed was discharged from inside the pre-filtration liquidreservoir bag and a converted weight of the post-filtration liquidrecovery bag ceased to increase, more specifically, the time required tofilter all of the liquid, was measured, and the measured time wasdefined as a total processing time (minutes). The weight of the liquidrecovered in the post-filtration liquid recovery bag was measured anddefined as a recovery amount (g). A mean processing speed (g/min) wasdetermined by calculation based on the recovery amount and the totalprocessing time. A difference between the 300 g of liquid that wasfilled into the pre-filtration liquid reservoir bag and the recoveryamount was determined by calculation, and defined as a loss amount (g).

Example 2

Filtering was carried out using a filter assembled by the same method asin Example 1, except that the periphery of the flow channel securingsheet continued as far as the second seal part, and the second seal partwas formed by sealing the inlet-side flexible container, the flowchannel securing sheet, and the outlet-side flexible container.

Example 3

Filtering was carried out using a filter assembled by the same method asin Example 2, except that sealing and assembly were performed such thatan outlet opening for allowing liquid to flow out from inside theflexible container to an outlet port overlapped with a lowermost portionof the first seal part (lowermost portion of a passage region formed bya valley part corresponding to the first seal part in a state in whichblood is flowing).

Example 4

Filtering was carried out using a filter assembled by the same method asin Example 2, except that sealing and assembly were performed such thatan outlet opening for allowing liquid to flow out from inside theflexible container to an outlet port overlapped with an uppermostportion of the first seal part (uppermost portion of a passage regionformed by a valley part corresponding to the first seal part in a statein which blood is flowing).

Example 5

Filtering was carried out using a filter assembled by the same method asin Example 2, except that a flow channel securing sheet having athickness of 0.8 mm was used.

Example 6

Filtering was carried out using a filter assembled by the same method asin Example 2, except that a first seal part was formed by disposing awelding frame sheet and the flow channel securing sheet in a layeredarrangement so as to sandwich the filter element therebetween,thereafter the outlet-side flexible container was overlaid on the flowchannel securing sheet side, and the inlet-side flexible container wasoverlaid on the welding frame sheet side to thereby form a second sealpart by clamping and sealing both the flow channel securing sheet andthe welding frame sheet between the outlet-side flexible container andthe inlet-side flexible container.

Comparative Example 1

Filtering was carried out using a filter assembled by the same method asin Example 1, except that a flow channel securing sheet was not used.

Comparative Example 2

Filtering was carried out using a filter assembled by the same method asin Comparative Example 1, except that a first seal part was formed bydisposing the inlet-side flexible container, the filter element, and theoutlet-side container in a layered arrangement, and thereafter thesecond seal part was formed.

Table 1 shows a summary of the results of Examples 1 to 6, andComparative Examples 1 and 2.

TABLE 1 Example Example Example Example Example Example ComparativeComparative 1 2 3 4 5 6 Example 1 Example 2 Priming Time 2.8  2.0 2.12.6 2.1 2.1 2.8 2.3 (min) Total Processing 17.3 17.6 17.5 17.1 16.0 17.826.1 26.4 Time (min) Recovery 257.9 260.2.8 259.9 259.3 258.4 260.0258.3 260.9 amount (g) Mean 14.9 14.5 14.9 15.2 16.2 14.6 9.9 9.9Processing Speed (g/min) Loss Amount 42.1 39.8 40.1 40.7 41.6 40.0 41.739.1 (g)

In Example 1, the total processing time is shortened and the meanprocessing speed is improved compared to Comparative Example 1. This isbecause, as a result of using the flow channel securing sheet in Example1, filter material at a distant position from the outlet port is alsoeffectively utilized and a situation does not arise in which the outletopening of the outlet port contacts the filter material and is blocked.More specifically, liquid that flowed out from various areas in a planardirection did not concentrate at one point of the outlet port, butrather flowed in diffuse directions through the slit portions of theflow channel securing sheet, passed through the passage regioncorresponding to the first seal part as a flow channel, flowed againinto the slit portions connected to the outlet opening of the outletport, and was discharged to outside the filter through the outlet port.

According to Example 2, the flow channel securing sheet continues as faras the second seal part. Consequently, there is no soakage to theprotruding nonwoven fabric portion or loss of liquid. The loss amountaccording to Example 2 is substantially equal to Comparative Example 2.Due to the effect of the slit portions of the flow channel securingsheet, a decrease in the priming time and total processing time wasobserved in comparison to Comparative Example 2, and a processing speedequivalent to that of Example 1 was obtained.

According to Example 3, the outlet opening of the outlet port isarranged so as to overlap with the lowermost portion of the first sealpart. Since the slit portions of the flow channel securing sheet and thepassage region are connected, and the effect is substantially the samewhether the outlet port is overlapping with the slit portions or thepassage region, the results for time and speed were approximately equalin Example 3 and Example 2.

Although the structure of Example 4 is equivalent to that of Example 3,the outlet opening of the outlet port is arranged so as to overlap withthe uppermost portion of the first seal part. Therefore, it is foundthat the priming time is longer than in Example 3. However, this is nota substantial extension of the priming time, but rather relates to thefact that the outlet port is disposed at the upper portion of the filterin order to carry out more complete priming and air bleeding. Morespecifically, it is because only air is discharged and liquid is notdischarged to outside the filter during priming, and hence the outletside of the filter is filled with liquid. Once liquid starts to flow outfrom the filter and the outlet-side circuit is filled with liquid, theliquid accumulated on the outlet side of the filter is rapidlydischarged to outside the filter by a negative pressure. Accordingly, amean processing speed that was the same level as that of Example 3 wasobtained without the apparent extension in the priming time extendingthe total processing time.

According to Example 5, although the blood processing filter isassembled in the same way as in Example 2, the thickness of the flowchannel securing sheet that is used is 0.8 mm, which is twice thethickness of the flow channel securing sheet used in Example 2. As aresult, although a certain increase in the loss amount was observed, theeffect produced by the slit portions of the flow channel securing sheetincreased, and a higher mean processing speed was obtained.

According to Example 6, the first seal part is formed so as to sandwichthe filter element with the welding frame sheet instead of theinlet-side flexible container. A mean processing speed of the same levelas that of Example 2 was obtained.

What is claimed is:
 1. A blood processing filter comprising a sheet-likefilter element, an inlet-side flexible container and an outlet-sideflexible container that sandwich the filter element and are sealedthereto, an inlet port provided in the inlet-side flexible container foraccepting blood before being processed by the filter element, and anoutlet port provided in the outlet-side flexible container fordischarging blood after being processed by the filter element; furthercomprising a flow channel securing sheet that is arranged between thefilter element and the outlet-side flexible container; a first seal partthat seals the inlet-side flexible container and the filter element in aband shape, and that is provided so as to surround the inlet port; andan annular second seal part that seals at least the inlet-side flexiblecontainer and the outlet-side flexible container, and that is providedso as to surround the first seal part at a position that is closer to anouter edge than the first seal part; wherein: a flow channel holethrough which blood that is processed by the filter element passes isformed in the flow channel securing sheet; and the outlet port isprovided so as to be capable of communicating with the flow channelhole; and a valley part corresponding to the first seal part is providedon an outlet side of the filter element, and at least one portion of theflow channel hole that is formed in the flow channel securing sheet isarranged in an empty space region that is formed by the valley part in astate in which blood is flowing.
 2. The blood processing filteraccording to claim 1, wherein: a plurality of the flow channel holes areformed in the flow channel securing sheet; and at least one portion ofall of the flow channel holes is arranged in the empty space region thatis formed by the valley part.
 3. The blood processing filter accordingto claim 1, wherein an outlet opening that communicates with an insideof the outlet-side flexible container is formed in the outlet port, andat least one portion of the outlet opening is arranged so as to overlapwith at least one of the flow channel hole and the valley part.
 4. Theblood processing filter according to claim 1, wherein the second sealpart sandwiches and adheres the flow channel securing sheet between theinlet-side flexible container and the outlet-side flexible container. 5.The blood processing filter according to claim 1, wherein the first sealpart sandwiches and adheres the filter element between the inlet-sideflexible container and the flow channel securing sheet.
 6. The bloodprocessing filter according to claim 1, wherein: the second seal partsandwiches and adheres the flow channel securing sheet between theinlet-side flexible container and the outlet-side flexible container;and the first seal part sandwiches and adheres the filter elementbetween the inlet-side flexible container and the flow channel securingsheet.
 7. The blood processing filter according to claim 1, wherein: theflow channel securing sheet is arranged so as to cover an effectivefiltering portion of the filter element; and a plurality of the flowchannel holes are formed in the flow channel securing sheet in a regionthat faces the effective filtering portion.
 8. The blood processingfilter according to claim 7, wherein, in the flow channel securingsheet, a proportion of a gross area of the flow channel holes withrespect to an area of the effective filtering portion is between 30% and99%.
 9. A method for manufacturing a blood processing filter comprisinga sheet-like filter element, an inlet-side flexible container and anoutlet-side flexible container that sandwich the filter element and aresealed thereto, an inlet port provided in the inlet-side flexiblecontainer for accepting blood before being processed by the filterelement, and an outlet port provided in the outlet-side flexiblecontainer for discharging blood after being processed by the filterelement; the method comprising: an installing step of arranging theinlet-side flexible container and the outlet-side flexible container soas to sandwich the filter element, and arranging a flow channel securingsheet in which a flow channel hole is formed through which bloodprocessed by the filter element passes, between the filter element andthe outlet-side flexible container; and a sealing step of sealing theinlet-side flexible container and the outlet-side flexible container ina state in which the filter element and the flow channel securing sheetare arranged at predetermined positions in the installing step; whereinthe sealing step includes a first sealing step of forming a first sealpart that seals the inlet-side flexible container, the filter element,and the flow channel securing sheet in a band shape so as to surround anarea where the inlet port is formed, without adhering the filter elementand the outlet-side flexible container, and a second sealing step offorming an annular second seal part that is formed so as to surround thefirst seal part at a position that is closer to an outer edge than thefirst seal part; a band-shaped valley part corresponding to the firstseal part is generated on an outlet side of the filter element by thefirst sealing step; and in the installing step, the flow channelsecuring sheet is arranged so that at least one portion of the flowchannel hole formed in the flow channel securing sheet is arranged in anempty space region that is formed by the valley part in a state in whichblood is flowing, and the outlet port is arranged at a position at whichthe outlet port is capable of communicating with the flow channel holeof the flow channel securing sheet.
 10. The method for manufacturing ablood processing filter according to claim 9, wherein: an outlet openingthat communicates with an inside of the outlet-side flexible containeris formed in the outlet port; and in the installing step, at least oneportion of the outlet opening is arranged so as to overlap with at leastone of the flow channel hole and the valley part.
 11. The method formanufacturing a blood processing filter according to claim 9, wherein:in the second sealing step, the flow channel securing sheet issandwiched and adhered between the inlet-side flexible container and theoutlet-side flexible container; and in the first sealing step, thefilter element is sandwiched and adhered between the inlet-side flexiblecontainer and the flow channel securing sheet.